CN108138604B

CN108138604B - Cogeneration system with power and heat capacity storage

Info

Publication number: CN108138604B
Application number: CN201680060916.3A
Authority: CN
Inventors: V·卡利卡
Original assignee: Pasteurization Technology Group Inc
Current assignee: Pasteurization Technology Group Inc
Priority date: 2015-09-23
Filing date: 2016-09-19
Publication date: 2021-07-13
Anticipated expiration: 2036-09-19
Also published as: KR20180044998A; AU2016328618B2; CA2998374A1; US20170082060A1; JP6746692B2; CN108138604A; EP3353386B1; WO2017053242A1; EP3353386A4; US9664140B2; JP2018536792A; EP3353386A1; AU2016328618A1

Abstract

A cogeneration system and method, said system comprising: a generator configured to generate electricity; a power storage configured to store and release power generated by the generator; an exhaust conduit configured to receive exhaust from the generator; a waste heat recovery device (WHRU) disposed in thermal communication with the exhaust conduit and configured to heat a fluid by transferring heat from the exhaust to the fluid; a tank configured to store fluid heated by the WHRU; a transfer conduit configured to circulate fluid between the WHRU and the tank; and an evaporator configured to evaporate liquid carbon dioxide using heat recovered from the exhaust gas.

Description

Cogeneration system with power and heat capacity storage

Cross Reference to Related Applications

This application claims priority to U.S. non-provisional application serial No. 14/862,843 filed on 23/9/2015, which is incorporated herein by reference in its entirety.

Technical Field

The present invention relates generally to Combined Heat and Power (CHP) systems, and more particularly to CHP systems configured to provide and store heat and electricity.

Background

CHP systems, which may also be referred to as cogeneration systems, are configured to simultaneously generate heat and electricity from one energy source. Such a system has tremendous efficiency, cost, and environmental benefits compared to a stand-alone energy production system.

Summary of The Invention

Exemplary embodiments of the present disclosure relate to a Combined Heat and Power (CHP) system, including: a power generation device configured to generate power; a power storage configured to store and release power generated by the power generation device; an exhaust conduit configured to receive exhaust from the power generation device; a waste heat recovery device (WHRU) disposed in thermal communication with the exhaust conduit and configured to heat a fluid by transferring heat from the exhaust to the fluid; a tank configured to store fluid heated by the WHRU; a transfer conduit configured to circulate fluid between the WHRU and the tank; and an evaporator configured to evaporate liquid carbon dioxide using heat recovered from the exhaust gas

An exemplary embodiment of the present disclosure relates to a method of operating a Combined Heat and Power (CHP) system, the system comprising: an electrical power generation device configured to generate electricity and exhaust gas; a Waste Heat Recovery Unit (WHRU) to transfer heat from the exhaust gas to the fluid; a tank configured to store a fluid; and a power storage, the method comprising: operating the CHP system in a first mode when the electrical load applied to the CHP system is substantially equal to the full electrical power output of the power plant and the external process requires substantially all of the heat transferred by the WHRU, the first mode comprising: operating the power plant at full power; applying the full electrical power output of the power generation device to an external load; transferring heat from the exhaust gas to a fluid; and supplying substantially all of the heating fluid to an external process.

The method further comprises the following steps: operating the CHP system in a second mode when the electrical load applied to the CHP system is less than the full electrical power output of the power plant and the external process requires substantially all of the heat transferred by the WHRU, the second mode comprising: operating the power plant at full power; applying a portion of the electrical power output of the power plant to a load; storing the excess electrical power output of the power generation device in an electrical power storage; transferring heat from the exhaust gas to a fluid; and supplying substantially all of the heating fluid to an external process.

The method further comprises the following steps: operating the CHP system in a third mode when the electrical load applied to the CHP system is substantially equal to or exceeds the maximum electrical power output of the power plant and the external processing requirement is less than all of the heat transferred to the fluid, the third mode comprising: operating the power plant at full power; applying the full electrical power output of the power plant to a load; applying the power stored in the power storage to a load; transferring heat from the exhaust gas to a fluid; and storing at least a portion of the heated fluid in a tank.

Brief Description of Drawings

Fig. 1 is a schematic diagram of a CHP system carbon dioxide vaporizer, according to various embodiments of the present disclosure.

Fig. 2 is a schematic diagram of a power generation device included in the CHP system of fig. 1, according to various embodiments of the present disclosure.

Fig. 3 is a schematic diagram of a CHP system including a carbon dioxide vaporizer, according to various embodiments of the present disclosure.

Fig. 4 is a schematic diagram of a CHP system including an electric heater, according to various embodiments of the present disclosure.

Fig. 5A and 5B are schematic diagrams of heat exchangers according to various embodiments of the present disclosure.

Detailed Description

The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the exemplary embodiments set forth herein. Rather, these exemplary embodiments are provided so that this disclosure will be thorough and will fully convey the scope of the invention to those skilled in the art. In the drawings, the size and relative sizes of layers and regions may be exaggerated for clarity. Like reference symbols in the various drawings indicate like elements.

It will be understood that when an element or layer is referred to as being "disposed on" or "connected to" another element or layer, it can be directly on or directly connected to the other element or layer or intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on" or "directly connected to" another element or layer, there are no intervening elements or layers present. It should be understood that for purposes of this disclosure, "at least one of X, Y and Z" can be interpreted as X only, Y only, Z only, or two or more items X, Y and Z (e.g., XYZ, XYY, YZ, ZZ). Here, when the first element is in "thermal communication" with the second element, heat may be transferred between the first and second elements.

Fig. 1 is a schematic diagram of a Combined Heat and Power (CHP) system according to various embodiments of the present disclosure. Referring to fig. 1, the CHP system includes a power generation device 10, a primary heat recovery device (WHRU)20, a power storage 30, a tank 40, an evaporator 50, and a control unit 60.

Generally, to achieve high efficiency in CHP systems, the power and heat loads should be perfectly matched to the power generation. When the power demand decreases, the power plant output typically decreases (load following), which also decreases the heat output. When the heat demand decreases, the waste heat is typically diverted to maintain the electrical output. Thus, both of these cases may reduce efficiency. Accordingly, various embodiments provide a CHP system configured to maintain high efficiency during changes in electrical and/or thermal demand.

An exhaust conduit 12 extends from the power plant 10 and through the WHRU 20 and the evaporator 50. The power line 14 extends from the power generation device 10 to an external load and a power storage 30. A recycle conduit 22 extends from the tank 40 through the WHRU 20 and back to the tank 40. The evaporation line 52 is from CO₂The source 70 extends through the vaporizer 50 and to the external CO₂A container or conduit (not shown).

The power generation device 10 may be any suitable device configured to generate electricity using a fuel such as natural gas, biogas, or the like. The power generation device 10 will be discussed in more detail below with respect to fig. 2. The exhaust duct 12 provides the hot exhaust gas output by the power plant 10 to the WHRU 20 and the evaporator 50.

The power generation device 10 may be connected to an external electrical load (not shown) and an electrical power storage 30 via an electrical power line 14 (e.g., an electrical bus or wire). The power storage 30 may include any suitable electrical storage device. For example, the power storage 30 may include one or more electrochemical storage devices, such as batteries, e.g., lithium ion batteries, nickel cadmium batteries, nickel metal hydride batteries, lead acid batteries, or flow batteries. According to some embodiments, the power storage 30 may include one or more super capacitors or power cells.

The power storage 30 may be configured to store excess power generated by the power generation apparatus 10. In other words, the power storage 30 may store more power than is required by the external load. Furthermore, the power storage 30 may be used to supplement the power generated by the power generation device 10 when the external load exceeds the power generation capacity of the power generation device 10.

The WHRU 20 may be configured as a heat exchanger having a shell and tube gas-to-liquid (e.g., air-water) configuration. As such, the WHRU 20 may be configured to heat a fluid, such as water, circulating in the circulation conduit 22 by extracting heat from the exhaust gas flowing through the exhaust conduit 12. The heated fluid may be stored in tank 40 for later use, or may be provided to external processing using output conduit 24. For example, heating fluid may be used to reduce the need for boiler heating. Tank 40 may be an insulated hot water storage tank, a boiler, a contaminated water storage tank, or any suitable hot water storage tank.

Further, additional fluid may be added to the system via an input conduit 26 connected to the recirculation conduit 22. In particular, the input conduit 26 may be connected to a pump or valve 28, the pump or valve 28 being configured to pass from the tank 40 and/or the input conduit 26 through the circulation conduit. The fluid may be, for example, non-potable water, glycol or water/glycol solutions, and or any other suitable insulating fluid. In some embodiments, the pump or valve 28 may be a valve configured to control the flow of fluid therethrough. In other embodiments, the pump or valve 28 may be a pump or a pump/valve combination.

The WHRU 20 may also be configured to pasteurize a fluid. In particular, the WHRU 20 may include a first chamber through which exhaust gas flows and a second chamber through which fluid flows. The chambers are configured to allow heat exchange between the exhaust gas and the fluid. The exhaust gas may have a temperature greater than the water pasteurization temperature (e.g., a temperature greater than 500 ℃, such as a temperature of about 250 to about 1000 ℃). As the fluid flows through the second chamber, the fluid may be heated to pasteurization temperatures due to heat exchange. The flow rate of the fluid through the chamber may be controlled to heat the fluid for a period of time and at a temperature sufficient to substantially sterilize/disinfect the fluid. Thus, if non-potable water is used as the fluid (e.g., the fluid supplied through input conduit 26), the non-potable water may be made safe for grey water applications. For example, pasteurized sterilizing water may be supplied from the output pipe 24 and used, for example, for irrigation or the like.

The control unit 60 may include a central processing unit and a memory. For example, the control unit 60 may be a server, a dedicated control circuit (e.g., an ASIC chip), or a general purpose computer loaded with appropriate control software. The control unit 60 may be integrated with the CHP system or may be electrically connected to the CHP system from a remote location.

The control unit 60 may be configured to control the operation of the CHP system. Specifically, the control unit 60 may detect a load applied to the power generation device 10, and may control whether the power storage 30 is charged or discharged accordingly. For example, the control unit 60 may charge the power storage 30 when the power output of the power generation apparatus 10 exceeds the applied load power demand, and may discharge the power storage 10 when the load power demand exceeds the power output of the power generation apparatus.

The CHP system may include temperature and/or level sensors in the tank 40 and/or the output line 24. Further, the control unit 60 may detect a demand for fluid in the tank 40. The control unit 60 may also detect when the liquid level in the tank 40 is below a threshold level and/or when the temperature 40 of the fluid in the tank is below a threshold temperature using a liquid level and/or temperature sensor in the tank. When the demand for heating fluid is low or non-existent (e.g., demand for output fluid from the output conduit 26), the control unit 60 may be configured to provide heating fluid to the tank 40 to the fluid in the circulation conduit 22 between the tank 40 and the WHRU by operating the pump or valve 28, or to heat the fluid in the tank 40 using a tank heater. When the tank 40 is filled with fluid heated to a desired temperature (e.g., the maximum operating temperature of the tank 40), the control unit 60 may open the valve 16 to divert exhaust gas into the diversion conduit 18. The control unit 60 may be configured to send control signals to the pump or valve 28, the valve 16, the power generation apparatus 10, and/or the power storage 30.

The evaporator 50 is disposed on the exhaust conduit 12 downstream of the WHRU 20 with respect to a direction of exhaust gas flow through the exhaust conduit from the power plant 10. As the WHRU 20 extracts heat from the exhaust gas, the temperature through the evaporator 50 may be lower than when the WHRU 20 receives the exhaust gas.

Typically, such relatively low temperature exhaust gases are not considered useful and are simply evacuated. However, the present inventors have discovered that such low temperature exhaust can be used in certain processes that require relatively low thermal energy. In particular, such cryogenic exhaust gas can be used to vaporize compressed liquid carbon dioxide, which is used by many breweries and food processors.

Accordingly, after passing through the WHRU 20, the low temperature exhaust gas in the exhaust conduit 12 is provided to the evaporator 50. Liquid CO₂Can be removed from CO via the evaporation pipe 52₂Source 70 (e.g., compressed CO)₂Storage container) is provided to the evaporator 50. The evaporator 50 may be configured as a shell and tube gas-to-liquid heat exchanger. As such, the vaporizer 50 may be configured to deliver liquid CO₂Conversion to gas (e.g. CO)₂Gas) which can then be provided for external use (e.g., for brewing or food processing). According to some embodiments, the evaporator 50 may be omitted.

Fig. 2 is a schematic diagram of components of the power generation apparatus 10 according to various embodiments of the present disclosure. Referring to fig. 2, the power generation device 10 may include an ignition chamber 100, a turbine 110, and an electrical power generation device 120. The power plant 10 may also include a blower or compressor 130, a compressor 140, and a combustor 150.

A fuel conduit 162 may connect compressor 140 and combustor 150 to fuel supply 160. Fuel supply 160 may be a pipeline, such as a natural gas pipeline, or may be a fuel storage tank containing hydrocarbon fuel. The hydrocarbon fuel may be, for example, natural gas, methane, propane, or butane. However, other fuels may be used. The compressor 140 operates to compress fuel and then supply the compressed fuel to the ignition chamber 100. In particular, fuel at a relatively low pressure (e.g., 80-120psig) can flow from the fuel source 160 to the compressor 140. The compressor 140 may then further pressurize the fuel to a relatively high pressure (e.g., 300-. Meanwhile, the blower or compressor 130 may be operated to feed room temperature air into the ignition chamber 100.

The ignition chamber 100 may include an igniter (not shown) such as an electric spark generator, a flame generator, or other similar devices. In the ignition chamber 100, the pressurized fuel is mixed with air and ignited, thereby generating gaseous exhaust gas having high temperature and high pressure.

Exhaust gas is supplied from the ignition chamber 100 to the turbine 110 at high speed through the turbine inlet duct 102. The high velocity exhaust gas flow rotates the blades of the turbine 110, creating rotation in an output shaft 112 that connects the turbine 110 to the electrical power generation device 120. The electrical power generation device 120 converts the rotation into electric power. According to some embodiments, a reciprocating engine may be used in place of the turbine 110.

Exhaust gas from the turbine 110 is delivered to the exhaust conduit 12. The combustor 150 may be disposed in fluid communication with the exhaust conduit 12 downstream of the turbine 110 and upstream of the WHRU 20 with respect to a flow direction of the exhaust gas. The burner 150 may receive fuel from a fuel source 160 and may include an igniter similar to the ignition chamber 100. An optional second blower or compressor 131 may provide air to the combustor 150, which allows the combustor 150 to act as an independent heat source and provide hot exhaust gas into the exhaust duct 12 where it may be mixed with exhaust gas from the turbine 110. The burner 150 may ignite the fuel to supply additional heat to the exhaust flow. In some embodiments, the combustor 150 may receive compressed fuel from the compressor 140. However, in other embodiments, the combustor 150 may be omitted.

Fig. 3 illustrates a CHP system according to various embodiments of the present disclosure. The CHP system of fig. 3 is similar to the CHP system of fig. 1, and therefore only the differences between them will be described in detail.

Referring to fig. 3, the CHP system includes an evaporator 54 disposed on or in fluid communication with the recirculation conduit 22 and connected to a carbon dioxide source 70 via an evaporation conduit 52. The evaporator 54 may be disposed downstream of the WHRU 20, with respect to the direction of flow of the fluid in the circulation conduit 22. The evaporator 54 may be configured as a heat exchanger having a plate and frame or brazed plate liquid-liquid heat exchange configuration. The evaporator 54 may have a direct heat exchange structure or an indirect heat exchange structure including water or ethylene glycol as a heat exchange medium.

Fig. 4 illustrates a CHP system according to various embodiments of the present disclosure. The CHP system of fig. 4 is similar to the CHP system of fig. 1, and therefore only the differences between them will be described in detail.

Referring to fig. 4, the CHP system includes one or more electric heaters 80, 81 (e.g., resistive heaters) disposed in thermal communication with the circulation conduit 22 and/or the tank 40 and electrically connected to the power generation device 10 and/or the power storage 30 via the power line 14. The

heaters

80, 81 may be configured to heat the fluid in the circulation duct 22 when the load applied to the power generation device 10 is less than the electrical power output of the power generation device 10. The

heaters

80, 81 are operable to convert excess power provided by the power plant 10 into heat that may be used to heat the fluid in the circulation conduit 22 and/or stored in the tank 40. In other embodiments, the heater 81 may be integrated with the tank 40 to directly heat the fluid in the tank 40. In various embodiments, the CHP system may include

heaters

80, 81 or one of the

heaters

80, 81 may be omitted.

The heater 80 may be disposed on the circulation duct 22 upstream of the evaporator 54, or may be included in the evaporator 54. Thus, heater 80 may be used to preheat the fluid in circulation conduit 22 so that carbon dioxide evaporation may begin before power plant 10 reaches operating temperature. Additionally, the heater 80 may be configured to directly or indirectly heat the evaporator 54 using power from the power storage 30 such that carbon dioxide evaporation may occur when the power plant is not operating. In other embodiments, the heater 80 may be configured to directly or indirectly heat the evaporator 50 of fig. 1, such that the evaporator 50 may be operated using the power storage 30 when the power plant 10 is not operating.

Fig. 5A and 5B illustrate

heat exchangers

200, 220, respectively, according to various embodiments of the present disclosure. The

heat exchangers

200, 220 may exemplify any WHRU and/or evaporator described above.

Referring to fig. 5A, the heat exchanger 200 may include a first chamber 202, a second chamber 204, the first chamber 202 and the second chamber 204 separated by a baffle 206. The first fluid may flow into the first chamber 202 through an input conduit 208 and out of the first chamber 202 through an output conduit 210. The second fluid may flow into the second chamber 204 through an input conduit 212 and out of the second chamber 204 through an output conduit 214. In some embodiments, the first fluid and the second fluid may be different exhaust gases, carbon dioxide, and working fluids such as water.

As such, the heat exchanger 200 may be a counter-flow heat exchanger with counter-flow fluid flow. However, in other embodiments, the input and output conduits of one of the

chambers

202, 204 may be reversed such that the heat exchanger 200 may be a co-current heat exchanger with co-current flow. In some embodiments, the heat exchanger may be a cross-flow heat exchanger with cross-flow fluid flow. Heat between the first fluid and the second fluid may be exchanged through the barrier 206.

Referring to fig. 5B, the heat exchanger 220 includes an outer chamber 222 and an inner chamber 224 separated by a partition 223. Outer chamber 222 may surround inner chamber 224. For example, the inner chamber 224 may be cylindrical and the outer passage 222 may be annular.

The first fluid may flow into the outer chamber 222 through an input conduit 225 and may exit the first chamber through an output conduit 226. The second fluid may flow into the inner chamber 224 through an input conduit 228 and may exit the first chamber through an output conduit 230. In some embodiments, the first and second fluids may be different exhaust gases, carbon dioxide, and a working fluid such as water.

According to some embodiments, a CHP system may include any combination of the elements shown in fig. 1-5B. For example, the present disclosure includes a CHP system that can include the evaporator of fig. 2, the evaporator of fig. 3, and/or the

heaters

80, 81 of fig. 4. The CHP system may also include any of the

heat exchangers

200, 220 shown in fig. 5A and 5B.

According to various embodiments, the present disclosure provides methods of operating a CHP system according to different output requirements. The method can comprise the following steps: operating the CHP system in a first mode when substantially all of the CHP system's electrical and thermal output is required; operating the CHP system in the second mode when less than the maximum power output of the power plant is required, while substantially all of the heat output of the CHP system is required; and operating the CHP system in the third mode when the power demand exceeds the power output of the power plant and the heat demand is relatively low.

In the first mode, the control unit may operate the power plant at full power output and may capture heat from the exhaust gas by circulating fluid in the circulation duct. The heated fluid may be provided directly to an external processor. Alternatively, the heating fluid may be stored in the tank and/or provided from the tank to an external process. The power output of the power plant may be provided to an external load.

In the second mode, the control unit may operate the power generation device at full power output. The generated power may be provided to an external load and any excess power may be stored in a power storage. The fluid may also be heated and stored in tanks, provided to external processes, or a combination thereof. Once the power storage is fully charged/full, the output of the power plant may be reduced to match the external heat demand. Alternatively, the power plant may be shut down and the burner may be used to heat the fluid and meet the heat demand.

In a third mode, the control unit may operate the power generation device at full power output, and electrical requirements exceeding the capacity of the power generation device may be compensated for by discharging from the power storage. The fluid may also be heated and stored in tanks, provided to external processes, or a combination thereof. If the fluid in the tank reaches/approaches the maximum operating temperature of the tank, exhaust from the power plant may be vented through an exhaust conduit. In the alternative, the flow of fluid through the circulation conduit may be stopped.

According to some embodiments, the method may include operating the CHP system in the fourth mode when all or less than all of the electrical output of the CHP system is required, and only the turbine exhaust can transfer heat, and thus cannot meet heat dissipation requirements. The fourth mode may include operating the power plant at full power output while operating the combustor.

The generated power may be provided to an external load and any excess power may be stored in a power storage. Since the power plant exhaust includes heat from the turbine exhaust and optionally from the combustor, the WHRU may recover additional heat than if the combustor were not operating. Thus, the fluid may be heated to a higher temperature, or the circulation rate of the fluid may be increased. Thus, the heat output of the CHP system may increase.

As mentioned above, the above-described method allows the power plant to operate at full power, even when the electrical and/or thermal demand is relatively low, by capturing excess electrical and thermal energy in the electrical storage and the tank, respectively. Therefore, the efficiency of the cogeneration system may be unexpectedly increased.

The foregoing description of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of the invention. The description was chosen in order to explain the principles of the invention and its practical application. It is intended that the scope of the invention be defined by the following claims and their equivalents.

Claims

1. A combined heat and power CHP system, comprising:

a power generation device configured to generate power;

a power storage configured to store and release power generated by the power generation device;

an exhaust conduit configured to receive exhaust from the power generation device;

a waste heat recovery device (WHRU) disposed in thermal communication with the exhaust conduit and configured to heat a fluid by transferring heat from the exhaust gas to the fluid;

a tank configured to store fluid heated by the WHRU;

a transfer conduit configured to circulate fluid between the WHRU and the tank;

an evaporator configured to evaporate liquid carbon dioxide using heat recovered from the exhaust gas; and

a controller configured to operate the CHP system, wherein:

in a first mode, when the electrical load applied to the CHP system is substantially equal to the full electrical power output of the power generation device, the controller is configured to operate the power generation device at full power, apply the full electrical power output of the power generation device to the electrical load, and store any heating fluid in excess of the external thermal treatment requirements in a tank;

in a second mode, when the electrical load applied to the CHP system is less than the full electrical power output of the power generation device, the controller is configured to operate the power generation device at full power, store excess electrical power output of the power generation device in the electrical storage, and store any heating fluid in excess of the external thermal treatment requirements in the tank; and

in a third mode, when the electrical load applied to the CHP system exceeds the full electrical power output of the power generation device, the controller is configured to operate the power generation device at full power, apply the full electrical power output of the power generation device to the electrical load, supplement the electrical power output of the power generation device with the electrical power output from the electrical storage, and store any heating fluid in excess of the external thermal treatment requirements in the tank.

2. The CHP system of claim 1, wherein the evaporator is disposed in thermal communication with the exhaust conduit downstream of the WHRU relative to a direction of exhaust flow through the exhaust conduit from the power generation device.

3. The CHP system of claim 2, wherein the evaporator comprises a shell and finned tube gas-to-liquid heat exchange structure.

4. The CHP system of claim 1, wherein the evaporator is disposed in thermal communication with the transfer line and is configured to recover heat from a heating fluid.

5. The CHP system of claim 4, wherein the evaporator comprises a plate and frame fluid-to-fluid heat exchange structure.

6. The CHP system of claim 4, wherein the evaporator comprises a bronze plate fluid-to-fluid heat exchange structure.

7. The CHP system of claim 1, further comprising an electric heater configured to heat the fluid using at least some of the power generated by the power generation device,

wherein the electric heater is configured to operate when an electrical load applied to the CHP system is less than a full electrical power output of the electrical generation device.

8. The CHP system of claim 1, further comprising liquid CO disposed in fluid communication with the evaporator₂A source.

9. The CHP system of claim 1, further comprising a burner configured to provide heat to the exhaust conduit.

10. The CHP system of claim 1, wherein the power generation device comprises a gas turbine or a reciprocating engine.

11. The CHP system of claim 1, wherein the power storage comprises a battery or a dynamic storage device.

12. The CHP system of claim 1, further comprising:

a valve disposed on an exhaust conduit between the power plant and the WHRU; and

an auxiliary exhaust conduit connected to the valve; wherein the controller is further configured to operate the valve such that exhaust gas is diverted into the auxiliary exhaust gas conduit when the fluid in the tank is near a maximum operating temperature of the tank.

13. The CHP system of claim 1, further comprising:

a pump or valve configured to circulate fluid in the transfer conduit;

wherein the controller is further configured to control the pump or the valve such that the pump or the valve stops circulating the fluid in the transfer conduit when the temperature of the fluid in the tank approaches a maximum operating temperature of the tank.

14. The CHP system of claim 1, further comprising an electrical heater electrically connected to the power storage,

wherein the electric heater is configured to heat the tank or transfer conduit using power from the power storage when the power generation apparatus is not operating.

15. A method of operating a combined heat and power, CHP, system, the system comprising: a power generation device configured to generate power and generate exhaust gas; a Waste Heat Recovery Unit (WHRU) to transfer heat from the exhaust gas to a fluid; a tank configured to store a fluid; and a power storage, the method comprising:

operating the CHP system in a first mode when the electrical load applied to the CHP system is substantially equal to the full electrical power output of the power plant and the external process requires substantially all of the heat transferred by the WHRU, the first mode comprising:

operating the power plant at full power;

applying the full electrical power output of the power generation device to the electrical load;

transferring heat from the exhaust gas to a fluid; and

supplying substantially all of the heating fluid to an external process;

operating the CHP system in a second mode when the electrical load applied to the CHP system is less than the full electrical power output of the power plant and the external process requires substantially all of the heat transferred by the WHRU, the second mode comprising:

operating the power plant at full power;

applying a portion of the electrical power output of the power generation device to the electrical load;

storing the excess electrical power output of the power generation device in an electrical power storage;

transferring heat from the exhaust gas to a fluid; and

supplying substantially all of the heating fluid to an external process; and

operating the CHP system in a third mode when the electrical load applied to the CHP system is substantially equal to or exceeds the full electrical power output of the power plant and the external processing requirement is less than the heat transferred to the fluid by all of the WHRUs, the third mode comprising:

operating the power plant at full power;

applying the electrical power output stored in the electrical power storage to the electrical load;

transferring heat from the exhaust gas to a fluid; and

storing at least a portion of the heating fluid in a tank.

16. The method of claim 15, wherein the second mode further comprises reducing the electrical power output of the power generation device after the power storage is fully charged.

17. The method of claim 15, wherein the third mode further comprises ceasing the transfer of heat to the fluid when the tank is near a maximum operating temperature.

18. The method of claim 17, wherein ceasing the transfer of heat to the fluid comprises exiting the exhaust from the WHRU or preventing the fluid from flowing through the WHRU.

19. The method of claim 15, further comprising transferring heat from the fluid or exhaust to vaporize the liquid CO₂。

20. The method of claim 15, wherein:

the fluid comprises waste water; and

transferring heat from the exhaust gas to a fluid includes pasteurizing the wastewater.